Swallow (deglutition) syncope and carotid sinus hypersensitivity

Swallow syncope is usually classified among the situational reflex syncope syndromes. Although by definition associated with swallowing, the precise trigger site(s) for swallow syncope is unclear. Herein we report two patients in whom swallow syncope occurred in conjunction with carotid sinus hypersensitivity (CSH). Patient 1 was a 63-year-old man whose swallow-induced symptoms comprised repetitive syncope and near-syncope while drinking water. Patient 2 was a 62-year-old man who, in addition to syncope, also experienced chest discomfort while drinking water. Ambulatory electrocardiograms (AECG) revealed symptomatic sinus pauses and paroxysmal AV block in Patients 1 and 2 respectively. During autonomic laboratory testing, each patient exhibited abnormal responses during both carotid sinus massage (CSM) and a cold liquid swallowing test. Patient 1 revealed a primarily cardioinhibitory (CI) response to swallowing and CSM, while Patient 2 exhibited principally a CI response to swallowing and a vasodepressor (VD) reaction during CSM. In conclusion, while CSH is common in older men and consequently its association with swallow syncope could thereby be a coincidence, the presence of both in the same patients raises the possibility that in some patients there may be concordance of trigger mechanisms within the pharynx and/or neck in these forms of reflex syncope. Further, the use of a swallowing test to distinguish the relative importance of CI and VD features in individual swallow syncope patients may be helpful for selecting an appropriate treatment strategy.